Spring-die.



O. A. SMITH.

SPRING DIE. APPLIOATION FILED 001. 22, 1912.

Patented Sept. 22, 1914.

INVENTOR 0:20pm A 5mil7a.

WITNESSES:

. UNITED STATES PATENT OFFICE.

. oscm A. SMITH, or onnvnnnnnyonro, Assmnoa '20 THE NATIONAL-ACME MANU- rac'runme. COMPANY, or CLEVELAND; OHIO, 1A.. CORPORATION or 01110.

. SPRING-DIE.

and useful Improvements in Spring-Dies,-

ofwhichthe following is aspecification.

This invention relates 'to dies, moreparticularly to that character thereof known as spring dies, the object of the invention being 'to provide an improved die of this classin 1 which the die can be. much more cheaply made and renewed and in which various sizes or -pitch: of'chasersor cutters-maybe used with the same body instead of, as here-,

:toforeyhaving a different body for each dif-. erent size or pitch of thread.

Spring-dies as-usually made, in view of =the :fact that the cutters or chasersare formed as an integral part of the. split ends thereof, must-have: the entire body: made from either carbon steel, at a cost of sixteen to eighteen centsa, pound, or, fromhigh speed-steel, at a-cost ofsixty to seventy cents pertpound, and whenthe-cutteis or chasers wear. out the: entire die-must be thrown away because, owing to its peculiar construction, it-cannot be worked over and therefore sim-.

- ply goes into the scrap pile. Furthermore,

with the old style die every diiferent diame- E teror pitch means an entire new body, therefore requiringa large number of die bodies to accord with the difierent pitches and diameters of threads to be cut. By means of the present improvement, however, I-manw facture the body or shell of machinery steel, carbonized, spring tempered .and spread open-at the split end, while the chasers or cutters are made independently thereof and the die is madef a much less expensive matherefore can be made of tool steel or; of; high speed steel as occasion may require. The-advantages of this improved'construc tion over the ordinary spring die are therefore many, for the reason that -machine r.y steel, of which the body itself is made, can be bought in the open market-for two -or three cents; per pound, as against sixteen to eighteen cents for carbon steel and as against sixty :to seventy cents for high speed steel, and therefore themajor part of terial. =Thechasers, however, are madeof the-desired carbon steel, or of high'speed steel, and when these chasers orcutters wvear out it is-on'lynecessary to replace them with Specification of Letters Patent. Pat t d 131; 22, 1914 v Application filed October 22, l912,- Serial-No. 7 27,'188. I

new ones of. thesam'esize and pitch of thread, or chasers having a different size and pitch of thread may be used with the same body, so that it is not necessary to use an entire-new body as the pitch or size of the thread is varied and the cost of the die is therefore very materially lessened because the chasers-as they are worn out maybe-dis- .carde'd, since-their cost is comparatively little 'owlng-to-the small amount of material therein. 'Furthermore,*by being able to remove the chasers a great advantage is obtained in the facility with which they may be ground. Moreover, the cost of manufacture is reduced'inanother way, as it is much easier to work-machinery steel, of which the bodyismade, thancarbon or highflspeed steel. In other words, -when' the entire die was-made. of the high priced steel! as heretofore necessary the cost of-manufacturing it was materially increased, because of the difficulty of working such steel; but by making the body of the low priced. steel, as in the present improvement, the cost of working it is: also reduced.

'In the drawings accompanying and formmg part of this specification, Figure 1 is a .side view, partlybroken away, showing this improved die; Fig. 2 is a front view thereof; and Fig. 3 is a View of one of the chasers aremoved'.

Similar characters of reference indicate corresponding parts in the different figures of the drawings.

' In the present improvement the die body or shell-2, which, as hereinbefore stated, is

made-of machinery steel carbonized and spring tempered, is splitat its end to form the spring-ended portion of the die, as at 3. The projections? are provided with recesses F4: in .which the removable or detachable chasers or-cutterso are located and secured in place each by a suitable screw 6. In the bottom. of each of these recesses is located a locating pin 7 adapted to project into the chaser for propeiflylocating-"and assisting in holding the chaser in position in the body. These Chasers or cutter blades are made of tool steel or high speed steel-as occasion may require, while, as stated, the body may be made of ordinary machinery steel, which is very "lowpriced as compared-with the costof the -,separable-fro nH-the-diebody it will be observed that various forms of chasers, that is chasers of different pitch or size may be used in the same die body and when such chasers are worn out may be readily renewed without the necessity of renewing the entire die bod Lbcated on the die body is a split'collar 8, which isbored to fit the diameter of the die body at the solid or unsplit end thereof as at 9. When the collar is adjusted to just fit this unsplit end and then forced to the extreme end of the split end of the'body it adjusts the die to the standard diameter of bore of chasers, and by screwing in or releasing the screw 10 of this collar the chasers may be adjusted to cut larger or smaller than the standard bore of the same.

In practice the recesses for receiving the chasers are of angular form and are formed in the tapered ends of the split spring formed projections, and the bore of the die body is larger throughout the major portion thereof than it is at the tapered ends of the projections.

Another feature of the present improvement consists in the manner'in which the detachable chasers are supported in the die body. It will be observed that the slots or recesses 12 which form the spring projections 3 are located out of alinement, see Fig. 2, with one another, although the chasers 5 are located in axial alinement with one an other. By reason of this peculiar construction it will be observed that there is more metal in the tapered chaser holding portions of the body at one side, as at 13, than there is at the other. This increased amount of metal is located on the side which receives the strain, and in consequence there is plenty of metal to receive such strain, for the reason that in practice the torsional strain on the chasers would come at the points 14 and 15, see Fig. 2, whereas if the recesses 4 were located in the tapered projections 3, with substantially the same amount of metal at each side of the chasers a considerable portion of the strain would come on the apex or pointed end of the projection at one side of the chaser. Furthermore, by locating the chasers in the manner stated a greater chip clearance space is provided where the chip curls, which is at the forward sides of the chasers, as at 16. In practice the chip as it is removed curls up the side 16 of the chasers, and by reason of the peculiar location of the recesses 4 it will be observed that there is only a small wall, as 17, to interfere with the chip, and consequently there is no appreciable tendency of this wall to throw back the chip against the chaser cutting teeth, as would be the case if the wall 17 were nearer to the cutting edge of the chaser.

In practice, for correcting any inaccuracy in the relative positions of the chasers, the

chasers are placed in their respective recesses in the die body and the screws 6 slightly turned so as to just take hold in the chasers. Then a pattern plug or arbor, which is an exact duplicate of the threads which it is-desired to cut on the work, is screwed in between the chasers,, after which the split collar 8 is set down just far enough over the split end of the die body'to leave the heads of the screws 6 exposed, and the collar tightened sufficiently to slightly compress the spring projections 3 of the die body. In this condition of the die any inaccuracy of the threads on the chasers can be corrected by striking the end of the plug or arbor, the loose condition'of the chasers permitting them to fall or be jarred into their proper positions on'the spiral plane, whereupon the clamping collar is fully tightened and the screws 6 screwed in, thereby to hold the chasers firmly in correct alinement with the threads of the plug against .which they are set, each individual chaser occupying its proper relative position on the spiral plane.

It will thus be seen that I have produced an improved s ring die which permits of a combined radial and longitudinal adjustment of the chasers, whereby the cutting points of the chasers may be brought di-= rectly into the proper relation to cut the desired spiral of the thread.

I claim as my invention:

1. In a .springdie, the combination of a die body having split spring projections, and detachable thereto. 2. In a spring die, the combination of a die body having split spring projections provided with recesses, and detachable chasers or cutters of a difierent material from that of the body secured in said recesses.

'3. In a spring die, the combination of a die body having split spring projections each having a recess therein, a detachable chaser of diflerent material from. that of the body fitting each of said recesses, means for securing eachof said chasers in its recess and comprising a locating pin carried by one of the parts and an opening carried by the other and threaded means projecting into said chasers, and a split clamping ring carried by the body for adjusting the split spring projections of the die toward and from the center.

4. In a spring die, the combination of a die body having split spring projections provided with recesses for the reception of chasers, detachable chasers jcarried by said recesses, the body and chasers being formed of diflerent materials,-means carried by the body and chasers for locating and securing said chasers in their recesses, and a detachable clamping ring adapted to fit. the 11th cutters or chasers secured split end of said body and to press the split projections toward the center of the die on the forcing of said clamping ring toward the split end of the die.

5. In a spring die, the combination of a die body having split spring formed projections provided with clearance spaces at each side thereof out of alinement, and detachable chasers carried by said projections in axial alinement with one another.

6. In a spring die, the combination of a die body having split spring formed projections provided with clearance spaces at each side thereof out of alinement, said projections having recesses, and detachable chasers carried by said recesses, said recesses being so located as to provide a greater amount of metal at one side of each chaser than at the other whereby a greater clearance space is provided at the forward side of the chaser.

7. In a spring die, the combination of a die body having split spring formed projections provided with clearance spaces at each side thereof out of alinement, said projections having recesses, and detachable chasers carried by said recesses said recesses being so located as to provide a greater amount of metal at one side of each chaser than at the other whereby a greater clearance space is provided at the forward side of the chaser, said chasers and die body being formed of diiferent materials.

OSCAR A. SMITH.

Witnesses:

F. E. Boron, J., B. McG mE. 

